Compensating piston lubricator



Mai-ch 15, 1 949. E. w. PATTERSON 2,464,710

COMFENSTING PISTON LUBRICATOR Filed June 3o, 1947 n I u in! ES Il Patented Mar. 15, 1949 UNITED STATES PATENT OFFICE 6 Claims.

This invention relates to air balanced pumping units such as shown in my United States Patent Reissue No. 20,287 and includes among its objects the provision of a collapsible piston oiler for the air balance chamber.

In the prior constructions such as above referred to, an air balance chamber is suspended beneath a pump arm or rocking beam and contains therein a stationary piston or plunger axially traversed by a hollow piston shaft which is in communication with an air reservoir having a constant pressure maintained by suitable pumping means. The balance chamber is moved up and down along the piston by the movement of the rocking beam to counter balance a portion of the weight of the fluid being lifted and the weight of the pump rods. It will be appreciated accordingly that the travel of the piston within the balance chamber varies with the stroke length of the pump. Consequently when operating conditions require a change of pump stroke, this changes the travel of the air balance piston in relation to the oil reservoir.

One of the requirements of such a balance chamber is that the walls adjacent the moving piston be continuously lubricated both to facilitate movement of the piston and also to seal this clearance space against air pressure loss or escape of air therealong. Accordingly an oil reservoir has generally been provided within the base of the chamber, into which the bottom of the piston is disposed to dip at the bottom of each stroke, the immersed end of the piston thus picking up oil which is wiped upward along the side walls to keep the chamber lubricated. However, the change of stroke length of the pumping unit changes the relation of the piston to the oil level in the reservoir and, under certain conditions, the piston does not dip into the oil unless the Oil level in the reservoir is raised to accommodate the new stroke length, or travel of the piston.

Checking the oil level is often overlooked when achange of stroke length is made and the air system loses pressure due to the loss of the sealing oil 4iilm which is necessary to hold air in a slow speed piston and cylinder of the size necessary to balance a well.

In addition, it should be apparent that it is necessary only for the piston to dip beneath the oil surface for a short distance in order to pick up the required lubricant so that 'as-long as the piston continues to contact the oil, the depth of the` latter may be quite shallow. On long stroke pumping units the cylinder and pistonvand oil reservoir must be quite long to accommodate the 2 variations in stroke length which is not true with this system.

Accordingly by the present invention there is provided an automatically adjusting, variable length piston having a collapsible section which is adapted to dip into such an oil reservoir regardless of changes of stroke length of the piston, and thereby to always continuously lubricate the balance chamber as long as there is any oil in the oil reservoir.

Other objects and advantages of the invention will be apparent from the following description and claims, the novelty consisting in the features of construction, combination of parts, the unique relations of the members and the relative proportioning, disposition, and operation thereof, all as more completely outlined herein and particularly pointed out in the appended claims.

In the drawings, which form part of the present specification: v

Figure 1 is a side elevational view of a pumping unit embodying the present invention;

Fig. 2 is an axial, vertical View partly in eleva.- tion taken through the air balance cylinder along the line 2-2 of Figure 1;

Fig. 3 is an axial sectional view along the base of the balance cylinder with the piston shown partly in elevation and positioned at the bottom of its stroke;

Fig. 4 is a transverse sectional View through the piston and balance chamber taken along the line 4-4 of Figure 2; and

Fig. 5 is a transverse partial sectional view through the piston and balance chamber, an alternate construction.

Asseen -particularly in Figure 1, there is provided a pumping unit supported jointly by a generally horizontal base 20, and an identical pair of upwardly extending, parallel members 22 disposed on opposite sides thereof. The individual members 22 are joined together by suitable bracing to form a vertically mounted Sampson post 24 and a pair of angular struts or supports 2B, the latter having their ends secured respectively to the top of the upright 24 and adjacent the horizontal base 20, being aiiixed at the latter point to vertical brackets 28. The lower end of the Sampson post 24 is in turn attached to a pair of mounting shoes 30 of the base by means of a horizontal pin 32.

The conventional, generally horizontal walking beam 34 is pivotally secured at one end to the top of the Sampson post 24 by means of a fulcrum shaft 36 and carries at its opposite end a horsehead 38 over which the reins 40 lof a pump f 3 `polish rod are led into a cross-bar 4| to which the polish rod 43 is attached. The base of the unit is located adjacent the well head in such manner that the horsehead will be located directly thereabove in the conventional manner.

An air reservoir tank 42 is located adjacent the Sampson post and mounted on the base Rotatably journalled in the conventional gear box 44 issaflow speed .drive shaft 45 .to the Vends of Which-Siskeyed aipair of cranl; arms liti, one on each side of the gear box. The shaft it is operatively connected to a power unit by suitable driving means not shown in detail.

A cylindrical air balance cylinder rt is pivot-- ally supported by a universal mountingironi -a cross-head 52 aflixed to the underside or the walking beam 34, the balance cylinder being thus adapted to reciprocate vertically along a stationary piston 54 supported within the chamber by a vertically disposed hollow piston rod 5t, which is pivotally mounted at its base. The Lipper end of the hollow piston rod communicates with theicylinder 5t and the lower end oi the hollow rod S55-communicates with the ail-,reservoir "42 -throughthepivotal base Y58 and air line "i lApa'ir of vertically vswinging pitman 1152i 'is 'ppi'votally secured to the cross-head `at its `upper end-andiattached by a terminal crank pin lbearinghousing-Gli to the crank arm t8 by 'means ofa horizontal crank pin |59 mounted in crank -arm=48.

Fixedlysecured'to the base adjacent theair reservoirby means of a footing member G8 is fan upright Y'compressor unit ill `having slidaoly extending from itsupper end a piston rod 4-connected to a vertically disposed pair of pitman rods i4 through a cross-head iii, the upper ends of the pitman rods being provided in turn lwith horizontal trunions 18 transversely disf posed in a dependent bracket 8@ of the walking v-beam.

The balance Acylinder .im is constructed of a 'tubular wall |80 attached to an annular top cios- -ure disk |92 by means of vertical bolts itil .n

serted through peripheral apertures in the disk and through aligned openings in an outwardly vextending flange H36 formed at the top or the *piston housing. The disk ieZ is secured to .the

`bottom of a suspension unit |68 held on the vvcross-head 52 by means yof a pair of upwardly extending-integral yoke members IIe `and i i2 `journalled on a central shaft H3 of the crassn head, the cross-head in turn Vbeing suspended beneaththerocking beam 34`by means ci a hanger ||4 bolted thereto. The balance cylinder may swing transversely on a 4longitudinal pin H5 so that universal movement is thus provided the two axes ||3 and H5.

fSecured across the bottom face of the piston chamber is a centrally7 apertured, annular plate 'H6 attached thereto by screws iifl and bearing' :an upwardly extending annular collar l2!) at its centenfadapted toreceive therethrough the holl'o'wpiston shaft 56. lThe collar |||ii serves to `dei-ine 'between its outer face and the inner sides of Ithe piston^chamber Van annular oil reservoir s|242.

' Ashere illustrated, the piston head or plunger V54-r`nounted on thetop of the piston shaft, consists of a generally cylindrical casting iifi fit l'on a circumferentially diminished terminal section |26 of the shaft. the plunger extending *somewhat 4'further down the ,housing from the baseof the diminished section and being formed withia-central -cavity -'|2| opening into the Ybaltained by a series of lugs.

ance chamber at the base of the piston. A number of piston rings |28 axially spaced'apart along the outer contacting surface of the plunger act to wipe the inner wall of the piston housing and thus provide a seal therealong.

At the base of the plunger there is formed an inwardly extending, annular shoulder |36 having a series of vertical apertures |32 spaced apart around the circumference .thereof and having individually mounted therein, a series of suspension bolts |34. This same result may be at- The lower ends of the bolts are received in a corresponding series of vertical apertures formed in an annulus |36 having similar dimensions to the lower shouldered extremity of the plunger and being axially spaced below therefrom a distance corresponding to the length of the suspension bolts. Both the shoulder |30 and the annulus |36 are radially spaced outward from the'piston shaft 56.

The upper outer edge of the annulus :is cut away so as to form an annular oil pocket '|38 therealong adjacent the wall of the piston'housing. Alternativelythe piston extensioirmaybe as shown in Figure 5in which the annular Ioil pocket |38 is omitted and where the loil onit'he annulus may drain toward the cylinderwalland deposit a film of oil `on the cylinder walLgso that upon this annulus 'being vimmersed in the oil reservoir `|22 uponth'e down stroke o'f the plunger, oil will cling to the slanting `surface on the inside of thebottom of the annulus '|36 and will drain down this slanting 'surface "to the cylinder wall and this oil will be thus `-deposited along thecylinder wall as thejplun'geris raised. This alternative is used if the desired depth of the oil in the reservoir |22 is shallow, as in Figure 5, and not deep enough to` permit the annulus |36 to be immersed and iill anannular oil pocket on top of 'the `annulus, as at |38 in Figures VV2 and 3. This alternative Avshown in Figure 5 is adequate for lubricating the'cylin der walls when the oil level in reservoir |22 is shallow, as in Figure 5. It will 'be seen also vthat upon the annulus abuting against ythe lower plate ISof the cylinder housing, and the plunger being pushed down yet further, the suspension ybolts |34 will move upward intothe central cavity "|21 of the ypiston head, or in other words the vtwo portions of the plunger `|24 and |36 will be co1- lapsed together as shown particularly in ,Figure 3.

At the upper rface of the plunger there is formed an annular well |42, Athe outer 4edg'e 4of which comprisesa radiusedl1ip.|4'4"adapted to channel into the well, oll wiped from Ithe cylinder walls by the upward movement of the piston. An annular cover plate |4615 mounted at ,thetop of the well |42 with its outer edge-spacedinward a short distance from the radiused lip |44 'an! disposed substantially iiush with the` air ,inlet 41 at the center of the piston shaft, the ,cover thereby preventing iair Ymoving through the hollow shaft from picking up or blowing awaytheoili-n the cup |42. `At thesame time, the 'Iilm of "oil maintained between the moving piston .andgth'e cylinder wall prevents ,air leaking ,therealong Provision is also madefor ,return to the lower reservoir |22 of oil gathered in the-cup .142,4by means of radial outlets |48,drilled into thebase of the cup from a peripheral groove in ,the side wall of the plunger. g y

It will thus beseen thatgl havel'produce'dasel'fadj ustinggpiston oiler which automatically cQmpensates 'for-varied strokedength ofthe drive shaft 4G or rocking beam 34 and facilitates a constant and even flow or lm of lubricant along the cylinder walls.

While I have shown and described in some detail a presenting preferred embodiment of my self-adjusting piston oiler, it is to be understood that various modifications may be made in the construction and operation thereof within the spirit and scope of the subsequently claimed invention which is to be construed broadly and limited only by the prior art.

I claim:

l. In a variable stroke pumping unit having a piston chamber, a variable stroke piston mounted lor reciprocal movement therein, and an open topped lubricant reservoir disposed within the chamber adjacent its base, the improvement comprising in combination therewith: a member having an outer perimeter corresponding to that of the piston and adapted to wipe the chamber wall, said member being slideably disposed beneath the piston within the chamber and being axially spaced from said piston by retractable means.

2. In a variable stroke pumping unit having a piston chamber, a variable stroke piston mounted for reciprocal movement therein, and an open topped lubricant reservoir disposed within the chamber adjacent its base, the improvement comprising in combination therewith: a member having an outer perimeter corresponding to that of the piston and adapted to wipe the chamber wall, said member being slideably disposed beneath the piston within the chamber and being axially spaced from said piston by retractable means, said retractable means being adapted to permit the member to be dipped into the lubricant during every stroke length of the pumping unit.

3. In a variable stroke pumping unit having a piston chamber, a variable stroke piston mounted for reciprocal movement therein, and an open topped lubricant reservoir disposed within the chamber adjacent its base, the improvement comprising in combination therewith: a member having an outer perimeter corresponding to that of the piston and adapted to wipe the chamber wall, said member being slideably disposed beneath the piston within the chamber and being axially spaced from said piston by retractable means, said retractable means being adapted to permit the member to be dipped into the lubricant during every stroke length of the pumping unit, said member having a lubricant retaining, peripheral groove formed along its upper edge adjacent the cylinder wall.

4. In a variable stroke pumping unit having a piston chamber, a variable stroke piston mounted for reciprocal movement therein, and an open topped lubricant reservoir disposed within the chamber adjacent its base, the improvement comprising in combination therewith: a member having an outer perimeter corresponding to that of the piston and adapted to wipe the chamber wall, said member being slideably disposed beneath the piston within the chamber and being axially spaced from said piston by retractable means, said retractable means comprising a plurality of longitudinal suspension pins disposed jointly in aligned apertures in the piston and in said member and adapted to move upward into a cavity in said piston upon further downward movement of the piston after said member is seated in the reservoir.

5. In a variable stroke pumping unit having a piston chamber, a variable stroke piston mounted for reciprocal movement therein, and an open topped lubricant reservoir disposed within the chamber adjacent its base, the improvement comf prising in combination therewith: a member having an outer perimeter corresponding to that of the piston and adapted to wipe the chamber wall, said member being slideably disposed beneath the piston within the chamber and being axially spaced from said piston by retractable means, said retractable means being adapted to permit the member to be dipped into the lubricant during every stroke length of the pumping unit, said retractable means comprising a plurality of longitudinal suspension pins disposed jointly in aligned apertures in the piston and in said member and adapted to move upward into a cavity in said piston upon further downward movement of the piston after said member is seated in the reservoir.

6. In a variable stroke pumping unit having a piston chamber, a variable stroke piston mounted for reciprocal movement therein, and an open topped lubricant reservoir disposed within the chamber adjacent its base, the improvement comprising in combination therewith: a member having an outer perimeter corresponding to that of the piston and adapted to wipe the chamber wall, said member being slideably disposed beneath the piston within the chamber and being axially spaced from said piston by retractable means, said retractable means being adapted to permit the member to be dipped into the lubricant during every stroke length of the pumping unit, said member having a lubricant retaining, peripheral groove formed along its upper edge adjacent the cylinder wall, said retractable means comprising a plurality of longitudinal suspension pins disposed jointly in aligned apertures in the piston and in said member and adapted to move upward into a cavity in said piston upon further downward movement of the piston after said member is seated in the reservoir.

EDGAR W. PATTERSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,227,845 Sleicher May 29, 1917 1,396,666 Rix Nov. 8, 1921 2,255,568 Page Sept. 9, 1941 

